Steam generating and superheating apparatus



STEAM GENERATING AND SUPERHEATING APPARATUS Filed Oct. 4, 1937 rRRr MAx H. KUHNER Stream;

Patented May 16, 1939 UNITED STATES PATENT OFFlCE STEAM GENERATING AND SUPERHEATING APPARATUS Application October 4, 1937, Serial No. 167,194

4 Claims.

This invention relates to steam generating and superheating apparatus, and more particularly to the construction and arrangement of a water tube steam boiler having a superheater and a reheater associated therewith.

It has been proposed heretofore to produce power by the expansion of superheated steam, and then to reheat the steam so that additional power may be produced by further expansion thereof Without undue condensation. For the most eflicient operation it is important to obtain high steam temperatures at the outlet of both the superheater and the reheater, and to control these temperatures accurately. Considerable difiiculty has been encountered in obtaining the'required accuracy in the control of the steam temperatures, particularly when both the superheater and the reheater are mounted in the same setting with the boiler.

It is accordingly one object of the invention to provide a comparatively simple and inexpensive apparatus for producing superheated steam and reheating the same, which is so arranged that the steam temperatures can be accurately controlled.

It is a further object of the invention to provide a compact and efficient apparatus including a water tube steam boiler, a superheater and a reheater, all mounted in a single setting, together with means for controlling the steam temperatures at the outlets of the superheater and the reheater independently.

With these and other objects in view, as will be apparent to those skilled in the art, the invention resides in the combination of parts set forth in the specification and covered by the claims appended hereto.

In accordance with my invention I provide a boiler and two steam heaters, preferably mounted in a common setting so constructed and arranged as to direct the hot gases from a combustion chamber into contact with the boiler and then into contact with the heaters successively. One of the heaters may be utilized to superheat the steam immediately following its generation, and the other may be utilized to reheat the steam after it has been reduced in temperature and pressure by expansion in a prime mover, such as a turbine. Associated with each heater is a bypass opening through which a portion of the hot gases can flow, thereby reducing the effectiveness of the heater. Means is provided to control the flow through the two openings independently, so that the temperature of the steam leaving each heater can be regulated as desired without affecting the operation of the other heater.

Referring to the drawing illustrating one embodiment of the invention, and in which like ref erence numerals indicate like parts, the single figure is a longitudinal vertical section through a water tube boiler and the steam heaters associ ated therewith.

The embodiment illustrated comprises a rear transverse steam-and-water drum H! and a rear transverse water drum ll therebeneath. These drums are connected by a bank of upright Water tubes 12, which may be spaced apart rather widely in each row since they are intended to serve primarily as downcomers rather than as steam generators. A transverse header or small water drum M is mounted in front of the water drum l l and at a somewhat higher elevation. Three rows of water tubes E5 extend upwardly and forwardly from the drum H to the drum i l, and two rows of water tubes [6 extend upwardly from the drum l4 and then at a slight upward slope rearwardly to the steain-and-water drum l0. These various parts are mounted in a setting shaped to provide a combustion chamber l8 beneath the tubes l5, this setting comprising a rear wall it, a front wall 25 and side walls ill. The rear wall 59 is protected by means of water tubes 23 connected at their upper ends to the drum 5 l, and the front wall 20 is protected by means of water tubes 24 connected at their upper ends to the drum H5. The side walls 2| may also be protected by water tubes if desired, but inasmuch as such constructions are well-known, and since an illustration thereof would greatly complicate the drawing and prevent a clear disclosure of the essential features of the invention, such water tubes have not been shown. It will be noted that the tubes it serve to support the roof 25 of the boiler setting. At the rear of the setting there is provided a gas outlet duct 26 which in the particular embodiment illustrated is located near the steam-and-water drum ll].

Suitable bafiles are provided to direct hot gases in a desired path from the combustion chamber l8 to the gas outlet duct 26. In the preferred construction a main baffle 28 extends forwardly from the water drum H and above the tubes l5 for a portion of the lengths of these tubes and then substantially vertically upward, terminating an appreciable distance below the roof 25. This baffle is supported and cooled by a row of water tubes 29 connected at their ends to the drums l8 and l I. A rear balile 38 extends downwardly from the drum iii and at the front of the down-corner tubes i2, terminating an appreciable distance above the lower drum H to provide an opening for the rearward flow of the gases. This baflie is supported and cooled by two rows of upright water tubes 3| connected at their ends to the drums l and II. With this construction hot gases from the combustion chamber l8 will flow upwardly in front of the bafile 28, rearwardly over the top thereof, thence downwardly in front of the bafile 30, rearwardly beneath the bottom thereof, and thence upwardly in the rear of the baflle 30 to the outlet duct 26.

The hot gases traveling through the setting are utilized not only to generate steam in the water tubes, but also to superheat this steam and to reheat the same. For this purpose there is provided a superheater comprising a group of sinuous tubes 33 located in front of the baffle 28 and connected at their ends to an inlet header 34 and an outlet header 35 mounted above the roof 25. The tubes 33 are supported intermediate their lengths by means of vertical rods 35 suspended from a beam 37. The inlet header 3 3 is supplied with steam from the steam-and-water drum it through a row of tubes 39. Steam from the outlet header 35 flows into a second group of superheater tubes 43 located adjacent the water tubes I and connected to an outlet header 4| mounted in front of the boiler setting. From the header M the steam may be delivered to any suitable apparatus, such as a steam turbine (not shown). In order to reheat the steam after it has been reduced in temperature in the turbine there is provided a reheater comprising a group of sinuous tubes 43 located between the baffles 28 and 30 and connected at their ends to an inlet header 44 and an outlet header 45 mounted above the roof E5. The t bes 43 are supported intermediate their lengths by means of vertical rods 46 suspended from a beam 41. It will be understood that suit able pipes (not shown) will be provided to deliver steam to the inlet header 44 and to withdraw the reheated steam from the outlet header 45.

Means is provided whereby the temperature of the steam leaving the superheater outlet header 4| and the temperature of the steam leaving the reheater outlet header 45 may be independently controlled. For this purpose both the superheater and the reheater are constructed with slightly greater heating surface than necessary to ensure suflicient heating of the steam, and associated with each of these heaters is a bypass opening or passage through which a portion of the hot gases can flow in such a way as to reduce the effectiveness of the heater. The gas flow in each passage may be controlled independently, thus allowing the desired regulation of the steam temperature. In the preferred construction illustrated an upright baffle 49 is mounted between the superheater tubes 33 and the bafile 28, these baflles being spaced apart to provide a vertical passage 50. The baiile 49 is supported and cooled by means of a row of water tubes 5| connected at their ends to the drums l0 and II. A damper 53 serves to regulate the gas fiow in the passage 50, this damper being controlled by means of a shaft 54 extending outside the setting. The rear bafile 30 is provided with an opening or passage 56 near the steamand-water drum l0 through which the hot gases may escape to the gas outlet 26 and avoid contact with a large part of the surface area of the reheater tubes 43. The flow through the opening 56 is regulated by means of a damper 51 which is controlled by means of a shaft 58 extending outside the setting. It will be noted that the reheater 43 extends below the opening 56 for such a distance that by adjusting the damper 51 the heat transfer to the reheater may be varied as desired.

The operation of the invention will now be apparent from the above disclosure. Any suitable fuel is burned in the combustion chamber l8, and the hot gaseous products of combustion travel upwardly therefrom across the water tubes l5 and the superheater tubes 45. Steam is generated in the tubes I5 and in the water wall tubes 23 and 24, and this steam flows through the tubes [6 to the drum l5, thence through the tubes 33 and the superheater tubes 33 and 40 to the header 4|. From this header the steam is withdrawn for use in a turbine or other prime mover and then returned to the tubes 43 for reheating. Just above the water tubes l5 the hot gases divide into two streams, a small portion of the gases entering the passage 55 and the remainder flowing in front of the bafiie 5! and in contact with the superheater tubes 33. This main gas stream flows rearwardly over the top of the baflie 5!, where it mingles with the small stream issuing from the passage 55 under control of the damper 53. Thereupon most of the ases flow downwardly in contact with the reheater tubes 43, beneath the lower edge of the bafile 3B, and thence upwardly in the rear of this bafiie to the gas outlet 25. A small stream of hot gases however flows rearwardly through the opening 55 under control of the damper 5?, these gases contacting with only a small portion of the reheater surface. If the temperature of the steam leaving the superheater header is too high, the damper 53 may be moved toward open position to reduce the gas flow over the tubes 33, and if the steam temperature is too low the damper 53 may be moved toward closed position to increase the gas flow over the tubes 33. These adjustments will not change the gas flow over the reheater 43 nor will they have any appreciable efiect on the temperature of the steam leaving the reheater. If the temperature of the reheated stream is too high, the damper El may be moved toward open position to reduce the gas flow over the lower portions of the tubes 33, and if the steam temperature is too low the damper 57 may be moved toward closed position to increase the gas flow over the lower portions of the tubes 43. These adjustments will not affect the gas flow over the superheater tubes or the temperature of the superheated steam.

It will now be apparent that the invention provides a comparatively simple and inexpensive construction, including a steam generator, a superheater and a reheater, all mounted in a single setting to form a very compact unit. The construction also includes a simple means whereby the temperature of the superheated steam and the temperature of the reheated steam may be controlled independently. The various baflies which direct the flow of the gases are well supported and cooled by water tubes. Moreover the upright arrangement of the baiiles ensures a gravity discharge of any soot which may be deposited on them by the gases.

Having thus described my invention, what I claim as new and. desire to secure by Letters Patent is:

1. Steam generating and superheating apparatus comprising an upper transverse steam-andwater drum, a lower transverse water drum, a substantially upright transverse balile located between the drums and having an upper opening and a lower opening therethrough, .a damper to control the upper opening, downcomers connecting the drums, water tubes extending upwardly and forwardly from the water drum, means connecting the front ends of the water tubes to the steam-and-water drum, a steam heater mounted above the front portions of the water tubes, a second steam heater mounted above the rear portions of the water tubes and in front of said transverse baflie, means providing a combustion chamber beneath the water tubes, a main baffle extending forwardly from the water drum beneath the second heater and then upwardly between the heaters, the hot gases flowing upwardly from the combustion chamber in contact with the first heater and thence rearwardly downwardly in contact with the second heater, means providing a by-pass for hot gases adjacent the first heater, and a damper to control the bypass, the second heater extending below the said upper opening for such a distance that by adjusting the first-mentioned damper the heat transfer to the second heater may be varied.

2. Steam generating and superheating apparatus comprising an upper transverse steam-andwater drum, a lower transverse water drum, a substantially upright transverse baffle located between the drums and having an upper opening and a lower opening therethrough, a damper to control the upper opening, downcomers con necting the drums, water tubes extending upwardly and forwardly from the water drum, means connecting the front ends of the water tubes to the steam-and-water drum, a steam heater mounted above the front portions of the water tubes, a second steam heater mounted above the rear portions of the water tubes and in front of said transverse bafiie, means providing a combustion chamber beneath the water tubes, a main baffle extending forwardly from the water drum beneath the second heater and then upwardly between the heaters, the hot gases flowing upwardly from the combustion chamber in contact with the first heater and thence rearwardly and downwardly in contact with the second heater, the first heater being spaced forwardly from the main baffie to provide a by-pass for hot gases, and a damper to control the by-pass, the second heater extending below the said upper opening for such a distance that by adjusting the first-mentioned damper the heat transfer to the second heater may be varied.

3. Steam generating and superheating apparatus comprising a rear transverse steam-andwater drum, a transverse water drum therebeneath, a rear baffle extending downwardly from the steam-and-water drum and terminating above the water drum, an opening in the upper portion of the baflle, a damper to control the opening, downcomers connecting said drums in the rear of the baffle, water tubes extending upwardly and forwardly from the water drum, means connecting the front ends of the water tubes to the steam-and-water drum, a steam heater mounted above the front portions of the water tubes, a second steam heater mounted above the rear portions of the water tubes and in front of said rear bafile, means providing a combustion chamber beneath the water tubes, a main baffle extending forwardly from the water drum beneath the second heater and then upwardly between the heaters, the hot gases flowing upwardly from the combustion chamber in contact with the first heater and thence rearwardly and downwardly in contact with the second heater, means providing a by-pass for hot gases adjacent the first heater, and a damper to control the by-pass, the second heater extending below said opening for such a distance that by adjusting the first-mentioned damper the heat transfer to the second heater may be varied.

4. Steam generating and superheating apparatus comprising a rear transverse steam-andwater drum, a transverse rear water drum therebeneath, a rear baffle extending downwardly from the steam-and-water drum and terminating above the water drum, an opening in the upper portion of the baifie, a damper to control the opening, downcomers connecting said drums in the rear of the baflie, a transverse front water drum, water tubes extending upwardly and forwardly from the rear water drum to the front water drum, a steam heater mounted above the front portions of the water tubes, a second steam heater mounted above the rear portions of the water tubes and in front of said rear baflie, water tubes extending upwardly from the front water drum and then rearwardly above the steam heaters to the steam-and-water drum, means providing a combustion chamber beneath the first-mentioned water tubes, a main bafile extending forwardly from the rear water drum beneath the rear heater and then upwardly between the heaters, an upright baffie between the front heater and the main baffle and spaced from the main bafiie to provide a passage through which a portion of the hot gases may flow upwardly from the combustion chamber, the remainder of the hot gases flowing upwardly in contact with the front heater, and a damper to control the flow in the passage, the second heater extending below said opening for such a distance that by adjusting the first-mentioned damper the heat transfer to the second heater may be varied.

MAX H. KUHNER. 

